Effects of inclusion stiffness on the cracking of cement-based composites under drying: a numerical study

Abstract

This paper focuses on the evolution of shrinkage cracking in a geometrically simplified concrete, i.e. a composite made of cement matrix including the glass spheres. In the first part, the laboratory samples at different levels of drying are examined experimentally. In order to identify the occurrence of cracking as well as its evolution in a direct and visual way, a non-destructive method called X-ray microtomography is used. The distribution of cracks is clearly identified, including their location and shape by the observation of cross section of samples. Based on the experimental investigations, a special coupled elastoplastic damage model is proposed to describe the mechanical behaviour of the composite. The obtained results satisfactorily reproduced the stress distribution and evolution in studied composite under drying and gave a better understanding of mechanical mechanism of shrinkage cracking. In order to study the influence of matrix behaviour and inclusion stiffness, a series of parametric studies are also performed by using a hydromechanical coupling code, incorporating the proposed constitutive model. One notices that the crack distribution in the sample depends strongly on the stiffness of inclusion and the mechanical behaviour of cement matrix.

Keywords:

• Cementitious composites
• drying process
• cracking
• hydromechanics
• elastoplastic damage
• inclusion stiffness